1. Field of the Invention
The subject of the present invention is a process for treating residues which are highly environmentally polluting via water, such as for example residues derived from dry or wet filtration.
The highly polluting residues targeted by the treatment process according to the present Application, are in particular sludge from metal production, sludge from decanters in mechanical engineering factories or iron and steel works, sludge from factory networks or from urban networks or also fines derived from dry or wet filtration of the fumes from coal-fired power stations or from industrial incinerators.
This type of residue contains particularly environmentally dangerous products.
In fact leaching tests carried out on these residues reveal that they contain products such as zinc, lead or cadmium which are highly polluting for the ground-water table when these residues come into contact with water.
2. Discussion of the Prior Art
Hitherto, several methods have been used to treat these residues which consist either in carrying out calcining of the residues at a temperature of the order of 1500.degree. C., or in packing the residues in order to store them in a hermetic enclosure or in absorbing the said residues by resins in order to avoid contact with water and air.
But these various methods are not economically profitable because, in the one case they require large energy consumption and in the other case they need refined and costly products of the noble resin, adhesive or special packaging type.